This invention relates to mattress, and more particularly to mattresses having means for adjusting the points and quantity of body support. The manner in which a patient's body is supported on a mattress can be very significant for preventing bedsores in bedridden patients. Normally when a person is at rest on a mattress, or asleep, there is a certain amount of natural body movement. This movement helps ensure that the skin at those parts of the body receiving the most pressure from the mattress, usually the bony protuberances, it not subject to excessive pressure over time. Unfortunately, many bedridden patients cannot move about on the bed sufficiently to avoid a constant pressure on these bony protuberances. The pressure can partially or totally block the skin capillaries, causing the cells to atrophy. This results in chronic bedsores, or what is medically called "decubitus". Aside from bedsores, which generally occur only with seriously ill, bedridden person, there is another problem which affects nearly everyone at one time or another. According to the New York Times (July 10, 1985 edition), 75 million people have been afflicted with back problems; 2 million people are chronically in pain and 8 million new cases occur each year. Back problems occur for a variety of reasons, including mattresses that do not offer proper support. Even when a mattress is not the initial cause of a backache, a mattress can aggravate or at least increase the discomfort of a backache because too much support, or insufficient support, are provided at particular points of the body. For example, a mattress which is designed to support a body evenly from head to foot will eventually, over time, develop a "soft spot" where the buttocks normally rest. This causes the back vertebrae to oriented in a position which in many people, will cause an irritation in the surrounding tissue and a backache. While many experts recommend a firm mattress to avoid or help backache (even to the point of inserting a wooden board beneath the mattress to increase firmness) (BC Cycle), Aug. 1, 1985 edition) others believe that a hard mattress has no therapeutic value and may even create morning backache (The Washing Post, June 17, 1983 edition). Thus there is no uniform opinion concerning the proper firmness of a mattress for purposes of alleviating ordinary back pain. Regarding bedsores careful attention and nursing, such as frequent rearrangement of the patient and bedclothes, can reduce this problem somewhat. The bedsores problem still remain largely unsolvent, and very little has been done to improve mattresses for otherwise healthy persons who suffer backache or other body pain which is exacerbated by a mattress.
A variety of special mattress structures and geometries have been proposed, primarily directed at the bedsores problem. For example, distribute mattress pressure more evenly, a water filled mattress supported by a heavy duty steel frame has been used. But such a water bed is exceptionally heavy and requires a heater to compensate for the water's convective cooling effect. Another device employs an air mattress core enclosed in a foam rubber box and uses an air compressor controllable by the user to vary the air pressure, and hence the firmness of the mattress. But such a system is complex and expensive and cannot easily alter the relative mattress pressure at any one point compared to the mattress as a whole. Another approach uses a layer of juxtaposed cells, each of which contains permanently sealed fluid-gel, covered by foam layers and a plastic sheathing. But while this fluid-gel flotation system reduces some pressure, it does not necessarily have the desired softness and air ventilation, and such special foam and fluid-gel cushions are expensive to manufacture.
Yet another approach is to make a three-piece mattress from foam blocks of different densities that can be placed adjacent to each other like building blocks to form the mattress. If desired, further bed cushions can be piled on top of this. But this is a clumsy arrangement without an integrating structure to simplify handling of the mattress as a whole.
An object of this invention is to provide a new and improved mattress for the reduction and prevention of bedsores and to alleviate discomfort for persons suffering from backache or other body pain. Another object is to provide a simple and inexpensive mattress structure that is easy to assemble, clean, and maintain. Yet another object is to provide such a mattress in a manner that allows easy and inexpensive "customizing" of the mattress configuration and characteristics to meet the needs of different persons, or the same person at different times, according to size, weight, and medical condition.